Anton and I have just brought CTD cast number 45 to light. While we are once again shaking freshly tapped bottles with great enthusiasm, I think I can make out question marks in Jamileh’s expression as she smiles good morning to us. That’s what everyone here seems to be thinking: 45 CTD casts already? And many of them in the same place? Why all this? We should know the water once we’ve “measured” it, right? Well, somehow we do.
“Our” CTD, which biologists prefer to call a “water sampler”, is moved out of the side of the hangar, lowered and in the basic version measures Conductivity (salinity), Temperature and pressure (Depth) quasi continuously (at 24 Hz), ideally down to the seafloor. In addition, oxygen and fluorescence are measured, which makes it possible to estimate biological productivity (see previous blog entries by Nicole and Manfred). As an addition, water samples can be taken at various depths using the 24 Niskin bottles (Manfred is by far our best customer in this respect). For oceanographers, however, the continuous measurements of temperature and salinity are of crucial importance, as they allow us to see how stable the water is stratified, for example, or to deduce the origin of the water masses and geostrophic currents. This is important information that forms the framework conditions that strongly influence the local ecosystem. In order to achieve maximum precision in the physical measurements, I take water samples myself “only” to calibrate the oxygen and salinity sensors later, but not to analyze the suspicious living beings in it.
Most of the deployments to date have been close to shore at a depth of about 1500 meters. The following figure shows one of our precious deeper profiles down to a depth of almost 3300 meters. Here, the top 100 meters form the so-called “mixed layer”, in which all measured variables are well mixed by the wind. We observe that the depth of this surface layer varies, but is generally comparatively thick – as is typical for the winter months at these latitudes. At our first station, the mixed layer depth was even around 200m! Temperature (red), salt (blue), oxygen (yellow) and chlorophyll (green) draw practically vertical lines in the diagram. Interestingly, a maximum of chlorophyll often forms exactly at or below the surface layer, which serves as an indicator for the presence of phytoplankton (see Nicole’s and Manfred’s blog entry on “Micro-Creatures”). Although phytoplankton is basically autotrophic, i.e. dependent on sunlight, it can survive in this rather deep layer with very little sunlight. One reason for this is the increased nutrient content in deeper layers.
In addition, the pycnocline directly below the mixed layer forms a strong physical barrier to vertical mixing and can practically “trap” organisms that cannot actively swim themselves. The pycnocline is the layer in which the density of the water increases very rapidly with depth (here due to the temperature gradient). These layers contain a wide range of temperature and salt contents and are also called Central Waters. To identify water masses, temperatures and salinities are plotted against each other in a so-called “T-S diagram” (as shown in Figure 4). In our example, you can clearly see that the water around Madeira consists largely of Eastern North Atlantic Central Water (ENACW). This water mass dominates the pycnocline in the large North Atlantic Gyre and is significantly more saline than in the South Atlantic (see Eastern South Atlantic Central Water). In our profile number 41 (Figure 3), however, something else catches the eye. At around 1100m, there is a nose with a significantly higher salinity, which does not seem to match the linear Central Water. The influence of the Mediterranean Water (MW) is noticeable here, which has a particularly high salt content due to the predominantly high evaporation and low precipitation in the Mediterranean region.
Due to this high salt content, it manifests itself at greater depths, typically around 1100m to 1200m, despite the warm temperatures. However, we can also see in the T-S diagram that the Mediterranean water in the south of Madeira is already somewhat more mixed, i.e. less warm and saline than directly at the outflow of the Mediterranean. Even further down, which we can observe particularly well at our deeper CTD stations around 3000m, resides the famous North Atlantic Deep Water (NADW). This is formed by, for instance, deep convection in the North Atlantic and plays a central role in global thermohaline circulation and climate dynamics. Although constituting deep water, it is comparatively “young” and therefore rich in oxygen (we like to say “well ventilated”) and forms a contrast to the oxygen minimum, which we observe here around Madeira at around 800-900 meters. This minimum zone is formed by respiration of the sunken organic material, e.g. from the sunlight-dependent phytoplankton in the uppermost ~150 meters. Compared to the large known oxygen minimum zones in the subtropical eastern Atlantic and Pacific, however, there is still comparatively abundant oxygen.
Now, we know the profile of a single CTD station a little better. Basically, this one is actually fairly representative of the other 44, so the question of why Anton and I keep “driving CTDs” like madmen remains unanswered. However, if we take a closer look, we can see that the temperature and salinity profiles are not completely “smooth”. In fact, we discover small wavelike deviations. Measurement inaccuracies? No. It is internal waves that bring “life” to the profiles. Internal waves can occur in any stratified medium, i.e. fluids in which the density is not constant. There are two restoring forces that act on internal waves in the ocean: Gravity and the Coriolis force. The main drivers of internal waves are the tides (such as ebb and flow), closely followed by wind. We know that internal waves play a crucial role in energy transport in the ocean. Like ordinary surface waves, internal waves can also break. When they do, mixing takes place. This in turn can transport nutrients and thereby influence biological productivity. The interaction of internal waves with topography (i.e. islands such as Madeira) and currents is very complex and not yet fully understood. By using a large number of stations at different times (and tidal stages), we obtain a better spatial and temporal resolution of the internal wave field and improve our understanding. That’s also why we are fans of so-called “yo-yo CTDs”. Just like a real yo-yo, we move the CTD up and down several times in direct succession at one and the same location.
In the figure above, we have plotted six directly consecutive profiles of a “CTD yo-yo” on top of each other. You can see that the profiles deviate more from each other at some depths and not at others (nodal points). The most impressive influence is exerted by internal waves on the mixed layer depth, which can vary by several tens of meters within minutes.
There is a particular thrill when the “Eddy hunt” is called for. That sounds more martial than it is meant to be. Eddies are oceanic vortices that reach a diameter of about 50 km around Madeira, interact with topography (islands) and internal waves and are known to have an impact on biodiversity. They develop over a period of days/weeks and are unfortunately hardly predictable. Therefore, we check satellite and model data for the region daily to identify a possible feature and, if possible, sample in situ with Merian. Strong eddies can generate a signal in sea level, surface temperatures and chlorophyll, recognizable via satellites. Our colleagues from the Oceanographic Institute of Madeira are helping us on site by providing the regional satellite and model data (see https://oomdata.arditi.pt/msm126/). Overall, it is impressive how well the collaboration on board and beyond works! One “eddy hunt” has already taken place on the night of February 13-14. However, the satellite signal was weak, and accordingly we were unable to detect a strong, coherent eddy In Situ with our shipboard ADCP (Acoustic Doppler Current Profiler, which measures ocean currents down to a depth of almost 1000m). (Side note: However, another exciting feature (presumably a strong internal wave) was identified in the surface layer, which we are now analyzing.)
In one of the following contributions, we want to prove to you that our beloved CTD is something very special in purely “objective” terms thanks to sophisticated tuning, including high-resolution camera systems. Then we’ll explain why Anton, although he’s not a physical oceanographer, also likes to drive “CTD yo-yos” and there will finally be photos of aquatic animals again!
Greetings from on board RV MARIA S. MERIAN,
Marco Schulz und Anton Theileis
It’s one of the best weeks of the year: Shark Week. As our finned friends get a lot of extra attention this week, I am reflecting on my love of sharks and the threats they’re facing. In fact, before I was an ocean plastics guy, I was a shark guy. And sadly, on a perfect sunny day in the tropics while searching for sharks, I also found plastics.
Two decades ago, I was researching these magnificent animals in the crystal-clear waters of the Turks and Caicos Islands (TCI) at the School for Field Studies. Each day, we’d take our research boats out in hopes of tagging juvenile lemon sharks to better understand their movements, site fidelity and nursing habitats in the shallow waters surrounding South Caicos. Every interaction with these animals was exhilarating, and quite often we’d get the bonus of spotting or tagging other species like bonnethead sharks, Caribbean reef sharks and even the awe-inspiring tiger shark—my personal favorite!
While out on shark patrol one Sunday afternoon along the eastern reef of South Caicos, I first encountered plastic pollution on a magnitude I had never previously seen. Due to the steep cliffs that backed the beach and the shallow reefs that protected it seaward, piles of plastics and debris that drifted over the reef and onto the sand remained stranded. And with little to no human access to these beaches in the early 2000s, the accumulations grew with each passing day.
Sharks are increasingly threatened by plastic pollution, primarily through entanglement and ingestion. At least 34 species have been reported entangled in plastic debris, although actual numbers are likely much higher due to underreporting. The most common item causing entanglement is abandoned, lost or discarded fishing gear (also known as “ghost gear”), though plastic strapping bands also pose a major risk. Looped plastics like strapping bands can constrict sharks, interfering with feeding and breathing.
Sharks are at risk from eating plastics, too. Plastic bags, plastic packets and even a boot have been found inside shark stomachs. And scientists believe microplastics may pose a particular risk to filter-feeding species like whale sharks, although hundreds to thousands of microplastics have been documented inside individual tiger and hammerhead sharks as well. There is still much more to learn and understand about the interactions and effects of plastics on sharks, but what is known raises concerns about the long-term impacts of plastic ingestion on shark health and ocean health more broadly.
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It was on that same reef in South Caicos in 2006, during a break from shark patrol and long before joining Ocean Conservancy where I first participated in the International Coastal Cleanup® (ICC). And like the millions of ICC volunteers around the world who participate each year, I too collected data on every item I picked up. And with each item, I was more and more curious, asking the questions: “Where did these plastics come from? “How the heck did they end up here?” and “This can’t be good for ocean animals, can it?”
I would later learn that the piles of debris that littered that stretch of coast came from all over the Caribbean. This was also my first glimpse of how the brands and languages on plastics provide valuable information to trace where trash comes from, an approach I still use to this day in fieldwork around the world. Further, it showcased the interconnectedness of the waters and people throughout the Caribbean Sea and North Atlantic Ocean.
These early, formative encounters with ocean plastics have stuck with me over the past 20 years, as have the sights of sharks effortlessly navigating their natural environments in those TCI waters. It is something that is forever lodged in my memory, something I never forget or tire of. Sharks have existed in our ocean for more than 400 million years, and over this time, they have perfected every aspect of their design. However, sharks were never meant to contend with the plastic pollution that now overwhelms every dimension of their marine environment.
Today, the most harrowing fact this Shark Week is that the plight of sharks has never been greater. And the scariest thing in the ocean isn’t a shark, it’s plastic pollution. Join Ocean Conservancy for Plastic Free July and beyond and call on your elected leaders to phase out wasteful, harmful single-use plastics.
The post How are Sharks Affected by Plastic Pollution? appeared first on Ocean Conservancy.
Nayyir Ransome builds relationships between the government and the people it serves to support the ocean. As Senior Analyst with Ocean Conservancy, Nayyir sees the power of small, incremental steps that lead to big impacts for people and waterways.
“I want to encourage people to start where they are. Start with your friends, your church group, your classroom”, Nayyir shared.
Nayyir started advocacy work when they were young, joining the Campfire Youth Legislature as a seventh-grade student in Broadmoor Middle School in East Baton Rouge Parish School System, a school that was closed in 2019. “I was one of the youngest people in the room. The bill that I proposed didn’t even make it out of committee. So, when it was time to come together on the floor and vote on all the bills that came out of committee, I decided that I was going to speak on every single bill that hit the floor, literally, all of them. I ended up winning Outstanding Legislator that year. This honor is given only to one legislator out of almost 500 young people from across the state. I still have the medal. I keep it on my desk lamp with all my other conference tags and medals. It reminds me how much impact a person simply speaking up can have. Whether or not the vote goes your way at that moment, someone is still listening.”
Nayyir got involved in Youth Legislature at a time in Baton Rouge, Louisiana, when many students were feeling unheard, anxious and facing physical displacement after Hurricane Katrina.
Remembering the day Hurricane Katrina landed
On August 29th, 2005, Hurricane Katrina made landfall in New Orleans. At least 1,900 people were killed in the storm and, due to medical and infrastructure complications, post-storm. The devastation of one of the deadliest hurricane seasons in United States history forced 650,000 survivors from their homes—some were never able to return.
“We were out of school for two weeks. Compared to New Orleans where many schools closed for months and others shut their doors permanently, this felt like a privilege. When we went back to school, there were 200 more students in the building. Many families from New Orleans were forced to move to temporary housing in Baton Rouge. Our school was one of many that saw a large influx of students from New Orleans where many schools were unable to reopen due to Katrina. There wasn’t enough space, services or support to handle that, and it became a tense environment for all of us.”
Nayyir’s family moved to Baton Rouge just one year before the storm. Coming from Philadelphia, one of the largest metropolitan cities in the country, Nayyir experienced an intense culture shock when adjusting to life in open-air, sea-centric Southern Louisiana. Nayyir reflected on the contrast of towering buildings and lightning-fast train transport to kids catching mudbugs from the crawfish mounds in the drainage ditches, designed to channel storm water, along roads without sidewalks.
“When I started participating in Camp Fire USA’s Youth Legislature program, I felt intimidated. It was a strange experience, grappling with my own sense of displacement while watching other kids being displaced on such a large scale due to Hurricane Katrina. I wasn’t from the area, but I was there, and I did understand how it felt to be pushed out, to feel discarded.”
New Orleans has a culture unlike any other place in the world, and this rich weaving of languages, ethnicities and histories creates an unshakable strength that still stands today. Yet, the crippling impacts of Hurricane Katrina can be traced through the yet-to-be-rebuilt homes in the Lower Ninth Ward and the reality of long-term health consequences and economic instability for many residents, even now, 20 years after the storm.
Hurricane detection is better than ever, thanks to NOAA
In 2005, the best hurricane detection science provided around a 48-hour warning. The people of New Orleans had less than 24 hours from the time the mandatory evacuation order was issued to when water began to spill over one of the levees.
When Hurricane Katrina developed into a Category 3 storm, receded and then reformed as a Category 5 storm, scientists, local officials and communities scrambled to keep up and spread information quickly.
“We didn’t know what was happening in New Orleans for three days. People with friends and family there were starting to panic.”
Now, thanks to the steady, decades-long efforts of organizations like the National Oceanic and Atmospheric Administration (NOAA), current predictive technologies can provide up to five days warning of extreme weather—enough time potentially to prevent storms from having the same catastrophic impact as Katrina. Yet, the question remains, ”Will we continue funding the hurricane forecasting systems we know are protecting our communities?”
Tell Congress to Protect NOAA Today
Take action to ensure Congress stands up for NOAA, demanding the agency be fully funded and fully staffed.
Understanding NOAA’s vital role during storm season
It might not be clear what NOAA does during hurricane season because much of their work is behind the scenes. The National Weather Service sits under NOAA, and NOAA scientists and professionals are key players in many of the long-term conservation measures, research and technology that prevent the most dire consequences of extreme weather. Their work includes projects that we may not think of as disaster preparedness and resilience, such as coastal restoration initiatives.
NOAA uses a variety of scientific instruments on crafts such as planes, saildrones and gliders to gather data from inside hurricanes. Long term ocean observations contribute to hurricane and weather models. This hurricane season we have an opportunity to speak up about the proposed cuts to NOAA and the vital resources we would lose if these budget changes are approved by Congress. Continuing to fund NOAA is one way to ensure ongoing improvements to weather forecasting, honor those lost to Hurricane Katrina and, in the aftermath, support the people of New Orleans today, as they rebuild and heal.
We can all speak up for life-saving hurricane detection and research
As storm seasons intensify, we need faster, more accurate weather prediction and storm detection more than ever. NOAA is America’s first line of defense against the deadliest impacts of natural disasters on our communities. Yet, NOAA’s funding is facing major cuts that, if enacted, will result in lives lost. We need to keep moving forward keeping in mind and heart the nearly 2,000 people who lost their lives during Katrina, the thousands more New Orleanians who lost their land and legacies, and the hundreds of thousands of people who are impacted by deadly storms in the United States each year.
Looking back, Nayyir can see how these experiences growing up in post-Katrina Louisiana shaped their advocacy and approach to community organizing.
“My time in Southeast Louisiana taught me a lot about people-centered advocacy. Even if we haven’t experienced something at its most extreme, we can find a way to understand the root of it by looking at our lives and the places we live. Ocean Conservancy has helped me to grow in how and why we must work across government agencies and lines to protect our ocean and the people who rely on it.”
Ocean Conservancy works alongside NOAA as a science-led advocacy organization mobilizing federal, state and local action for our ocean. Every investment in NOAA translates into vital seconds, hours and days of response time for communities when hurricane season strikes. The more data we can collect and use to predict the behavior and patterns of storms, the better we can respond and prevent tragedies.
Each year, storm season is intensifying from climate change—and not just on our coasts. Communities throughout the U.S. are affected by hurricanes and floods that threaten lives and livelihoods. We all rely on NOAA’s vital research and tools for weather prediction and extreme weather warnings. These services are a lifeline we cannot afford to lose.
Call on your Congress members today and insist they support full funding and operation of NOAA.
The post Honoring New Orleans 20 Years After Hurricane Katrina Means Protecting NOAA appeared first on Ocean Conservancy.
Honoring New Orleans 20 Years After Hurricane Katrina Means Protecting NOAA
Ocean Conservancy’s annual Photo Contest has come to a close and the results are breathtaking. Hundreds of you sent inspirational and heartbreaking photos and videos, and I am so impressed. Thank you for sharing your art with us. Discover the beautiful, inspiring and heartbreaking submissions that won the hearts of our judges, our staff and ocean lovers like you.
I am thrilled to announce the winners of Ocean Conservancy’s 2025 Photo Contest.
Judge’s Choice Winner
The Art of Survival by Rickie Andrés Ballesteros Guerrero
Follow Andrés on Instagram
From the Photographer:
“A blue-footed booby from the Galapagos Islands breaks the ocean’s surface in a swift and precise flight. With its wings spread and eyes focused, it catches a gleaming fish in its beak. The water splashes around it in a fleeting but powerful scene of the natural balance between predator and prey.”
What our Judges had to say:
“A moment frozen in time – this one stopped me in my tracks. A brief beat in the natural world, captured spectacularly.” – Pier Nirandara, 2025 Ocean Conservancy Photo Contest Judge
“An excellent photo of feeding and fighting for survival. The composition, light and action are perfectly captured. A great job by the photographer who patiently waited for the right moment to shoot. Great work.” – Mariano Rodríguez, 2025 Ocean Conservancy Photo Contest Judge
“This is a standout capture of a decisive moment. The image is sharp, emotional and dynamic. You can feel the energy of the hunt. It’s the kind of photo that brings nature’s raw beauty front and center—and reminds us of the power and grace within every species.” – Angela J. Farmer, 2025 Ocean Conservancy Photo Contest Judge
“A fantastic shot. He shot fast enough to freeze the exact moment. Lighting is good and also post processing. Love it.” – Joaquín Fregoni, 2025 Ocean Conservancy Photo Contest Judge
See more wonderful ocean animals!
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Staff Choice Winner
Sunset Whale Tail in Front of Eagle Glacier by Harvey Hergett
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From the Photographer:
“On the last whale watching trip of the summer with Jayleen’s Alaska, as the sun was setting on a perfect September day in Alaska, she positioned the boat perfectly in front of Eagle Glacier to capture this humpback whale who was playfully tail and fin slapping.“
What our staff had to say:
“I recognized this beautiful spot outside of Juneau right away! One of the things I love about Alaska is that there is always magic if you know where and how to look for it. Thank you for sharing this little slice of my home.” – Mike Levine, Senior Director, Alaska Programs
People’s Choice Winner
Manatee Love! by Paige Taggart
From the Photographer:
“This was taken in Crystal River, Florida when a curious juvenile manatee was investigating me while I was snorkeling the springs.”
What our staff had to say:
“Manatees have a special place in every Floridian’s heart, and anybody who’s ever visited the Sunshine State and seen these gentle giants up close and personally can attest to their awesomeness. With their round bodies and curious personalities, they perfectly embody the uniqueness of the Floridian environment and remind us of how important it is to protect our special and beloved ocean and coasts.” – J.P. Brooker, Director, Florida Conservation
We’d like to extend our deepest thanks to all who participated, voted, shared and submitted photos—you truly made this year’s contest a success. And a very special thank you to our judges: Angela J. Farmer, Joaquín Fregoni, Pier Nirandara and Mariano Rodríguez for lending their expert eyes to evaluating our finalists and determining our grand prize winner. Learn more about our judges here.
Congratulations to ALL our entrants, and we hope to see you next year.
The post Introducing Ocean Conservancy’s 2025 Photo Contest Winners appeared first on Ocean Conservancy.
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